Stress State and Earthquake Triggering on the Outer Rise of the Southern Vanuatu Subduction Zone, Southern New Caledonia

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Bulletin of the Seismological Society of America Pub Date : 2023-10-03 DOI:10.1785/0120230107

Shao-Jinn Chin, Rupert Sutherland, Martha K. Savage, Julien Collot, Olivier Monge, John Townend

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引用次数: 0

Abstract

ABSTRACT An analysis of earthquakes recorded in southern New Caledonia (SNC) over 14 months during 2018–2019 reveals focal mechanisms consistent with a normal-faulting stress state. The minimum principal stress is perpendicular to the Vanuatu subduction zone (VSZ), which is 200 km away, and is highly oblique to the local topographic ridge of New Caledonia, which may induce additional tension. An Mw 7.5 earthquake occurred in VSZ on 5 December 2018, and focal mechanisms appear to be different to those before the big earthquake. Significant increase in seismicity rates in both VSZ and SNC are observed following this large earthquake. A strong correlation between local and subduction zone seismicity rates is confirmed by analyses of seismic records before and after large subduction zone earthquakes 200–350 km away during the period of 2000–2018. The local seismicity rate and seismic hazard in SNC is about four times higher immediately after a large subduction earthquake, and Omori decay returns it to background levels after about 30 days. The triggering mechanisms remains unclear, but our study provides the first observations and a framework for future work.

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新喀里多尼亚南部瓦努阿图南部俯冲带外隆起的应力状态和地震触发

对新喀里多尼亚南部(SNC) 2018-2019年间14个月记录的地震进行分析，揭示了与正常断层应力状态一致的震源机制。最小主应力垂直于200公里外的瓦努阿图俯冲带(VSZ)，并与新喀里多尼亚当地地形脊高度倾斜，这可能会引起额外的张力。2018年12月5日VSZ发生7.5 Mw地震，震源机制与大地震前不同。在这次大地震之后，VSZ和SNC的地震活动率都显著增加。通过分析2000-2018年期间200-350公里外的大俯冲带地震前后的地震记录，证实了局部和俯冲带地震活动率之间的强相关性。大俯冲地震发生后，SNC的地震活动性和地震危险性高4倍左右，约30天后，Omori衰变使其恢复到本底水平。触发机制尚不清楚，但我们的研究提供了第一个观察结果和未来工作的框架。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Bulletin of the Seismological Society of America 地学-地球化学与地球物理

CiteScore

5.80

自引率

13.30%

发文量

140

审稿时长

3 months

期刊介绍： The Bulletin of the Seismological Society of America, commonly referred to as BSSA, (ISSN 0037-1106) is the premier journal of advanced research in earthquake seismology and related disciplines. It first appeared in 1911 and became a bimonthly in 1963. Each issue is composed of scientific papers on the various aspects of seismology, including investigation of specific earthquakes, theoretical and observational studies of seismic waves, inverse methods for determining the structure of the Earth or the dynamics of the earthquake source, seismometry, earthquake hazard and risk estimation, seismotectonics, and earthquake engineering. Special issues focus on important earthquakes or rapidly changing topics in seismology. BSSA is published by the Seismological Society of America.